1. Field of the Invention
This invention relates to patient activated temperature-controlled surface. More particularly, this invention relates to a heated or cooled surface that is activated by the weight of the patient upon the patient's body contacting, directly or indirectly, the heated or cooled surface. The heated or cooled surfaces of the present invention may be a mat or bed of any shape suitable for use by a patient that is a human being, animal or creature.
2. Brief Description of the Background Art
Heated or cooled surfaces for patients, including pets or livestock or other animals, are known. For example, U.S. Pat. No. 4,591,694 provides a heated pet bed having a shell that is filled with a water layer. A heater is provided with a thermostat below an enclosure filled with water. The thermostat controls the temperature of the water layer above which the pet lays. U.S. Pat. No. 4,332,214 describes a heated bed for animals having an electric heater in a water compartment which surrounds a platform on which a pet rests.
Another example of a heated place for animals is set forth in U.S. Pat. No. 5,261,352. A heated space for cold blooded animals having a casting or molding of a rock-like formation is disclosed wherein a heating device is embedded within the material of the rock-like formation.
U.S. Pat. No. 6,084,209 provides a heating pad for animals consisting of a plastic housing and an electric heating element. The base of the housing contains conical supports upon which the heating element rests. The heating element is supported in the housing to provide air gaps above and below the heating element, allowing an even temperature throughout the housing. The heated pet bed set forth in U.S. Pat. No. 6,084,209 is concerned with preventing regions of localized heat on the top of the bed and also preventing unnecessary heating of the base. U.S. Pat. No. 6,189,487 provides a heated animal bed that includes a hollow blanket casing within which is disposed at least three layers of foam insulation material placed on top of another. A removable heating element is interposed between two adjacent layers of the foam material and supplies heat to the animal resting on the bed.
U.S. Pat. No. 6,237,531 describes a heated and cooled portable pet bed having an open structure with a hollow ring around its periphery. The ring traps air to provide a thermal barrier for the pet. A thermoelectric unit is mounted to its underside with appropriate ducting for air circulation so that either heating or cooling is provided to a sink which is integral with the platform of the bed.
In spite of this background art, there remains a very real and substantial need for a patient activated temperature-controlled surface as provided by the instant invention for providing either heat or cold to a surface only when the patient's body weight has activated either directly or indirectly the actuator element for turning on the temperature-controlled surface to which the heat or cold is supplied, such as for example a bed on which an animal may rest.